JP2007022805A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming device capable of quickly correcting paper bending of a transfer material caused in a conveyance path and improving production efficiency. <P>SOLUTION: In this image forming device provided with a pair of conveyance rollers for conveying the transfer material in the conveyance path for conveying the transfer material, inclination to a conveyance face in the axial direction of the pair of conveyance rollers can be displaced. This image forming device is provided with a pressing pressure adjusting means for adjusting pressing pressure for the pair of conveyance rollers, and either of the pair of conveyance rollers is constituted to adjust balance of pressing pressure force to the other of them in the axial direction. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus capable of correcting skew (paper bending) of a recording material conveyed along a conveyance path.

  Conventionally, the conveyance position adjustment of a transfer material as a recording material is performed by adjusting the position of the conveyance roller by the inclination adjustment unit and the position adjustment unit of the conveyance roller after detecting the skew and deviation of the transfer material.

As an example of the position adjustment, an inclination detection means for detecting an inclination and a position detection means for detecting a position with respect to a direction orthogonal to the transfer material conveyance direction are both arranged downstream of the conveyance roller pair, and the conveyance roller A method has been proposed in which the detecting means detects the inclination and position of a transfer material that is sandwiched between pairs, and corrects the inclination and misalignment of the transfer material in accordance with the detection result (for example, see Patent Document 1). ing.
Japanese Patent Laid-Open No. 10-67448

  In the present invention, the skew of the transfer material (hereinafter also referred to as paper bending) generated in the transport path is more quickly performed by a method different from the correction and displacement means of the recording material disclosed in Patent Document 1. An object of the present invention is to provide an image forming apparatus which has been corrected and improved in production efficiency.

  The above object is achieved by the following configuration.

  (1) An image forming apparatus including a conveyance roller pair for conveying a recording material to a conveyance path for conveying a recording material, wherein the conveyance roller pair is capable of displacing an inclination with respect to an axial conveyance surface. Forming equipment.

  (2) In an image forming apparatus including a pair of conveyance rollers for conveying a recording material to a conveyance path for conveying a recording material, one of the conveyance roller pairs is configured to be capable of adjusting a pressing force balance with respect to the other in the axial direction. An image forming apparatus.

  The recording material without paper bending can be stably conveyed, and the positional accuracy of the image with respect to the recording material is improved.

  Hereinafter, an image forming apparatus having a pair of conveyance rollers capable of adjusting the paper bending according to the present invention will be described.

  In the description of the embodiment of the present invention, the technical scope of the present invention is not limited by the terms used in this specification.

  FIG. 1 is a schematic diagram illustrating an example of the overall configuration of the image forming apparatus.

  In FIG. 1, 10 is a photoconductor, 11 is a scorotron charger as charging means, 12 is a writing device as image writing means, 13 is a developing device, 14 is a cleaning device for cleaning the surface of the photoconductor 10, 15 Denotes a cleaning blade, 16 denotes a developing sleeve, and 20 denotes an intermediate transfer belt. The image forming unit 1 includes a photoconductor 10, a scorotron charger 11, a developing device 13, a cleaning device 14, and the like. The mechanical configuration of the image forming unit 1 for each color is substantially the same. Reference numerals are given to the configuration of only the Y (yellow) series, and the reference numerals are omitted for the constituent elements of M (magenta), C (cyan), and K (black).

  The arrangement of the image forming means 1 for each color is in the order of Y, M, C, K with respect to the running direction of the intermediate transfer belt 20, and each photoconductor 10 contacts the stretched surface of the intermediate transfer belt 20. The contact point rotates in the same direction as the traveling direction of the intermediate transfer belt 20 and at the same linear speed.

  The intermediate transfer belt 20 is stretched around a driving roller 21, an earth roller 22, a tension roller 23, a static elimination roller 27, and a driven roller 24. The belt unit 3 includes these rollers, the intermediate transfer belt 20, a transfer device 25, a cleaning device 28, and the like. Configure.

  The intermediate transfer belt 20 is driven by rotation of the driving roller 21 by a driving motor (not shown).

  The photosensitive member 10 is formed by forming a photosensitive layer such as a conductive layer, an a-Si layer, or an organic photosensitive member (OPC) on the outer periphery of a cylindrical metal base formed of, for example, an aluminum material, and the conductive layer is grounded. In the state, it rotates counterclockwise as indicated by the arrow in FIG.

  An electrical signal corresponding to the image data from the reading device 80 is converted into an optical signal by the image forming laser, and is projected onto the photoconductor 10 by the writing device 12.

  The developing device 13 is a developing sleeve formed of a cylindrical non-magnetic stainless steel or aluminum material that maintains a predetermined interval with respect to the circumferential surface of the photoconductor 10 and rotates in the same direction as the rotation direction of the photoconductor 10. 16.

The intermediate transfer belt 20 is an endless belt having a volume resistivity of 10 ⁶ to 10 ¹² Ω · cm. A semiconductive seamless belt having a thickness of 0.04 to 0.10 mm, in which a conductive material is dispersed.

  A transfer unit 25 has a function of transferring a toner image formed on the photoreceptor 10 onto the intermediate transfer belt 20 by applying a direct current having a polarity opposite to that of the toner. As the transfer unit 25, a transfer roller can be used in addition to the corona discharger.

  Reference numeral 26 denotes a transfer roller which can be brought into contact with and released from the earth roller 22 and retransfers the toner image formed on the intermediate transfer belt 20 onto a transfer material P as a recording material.

  A cleaning device 28 is provided to face the driven roller 24 with the intermediate transfer belt 20 interposed therebetween. After the toner image is transferred to the transfer material P, the intermediate transfer belt 20 has the charge of the residual toner weakened by the neutralizing roller 27 to which an AC voltage superimposed with a DC voltage having the same or opposite polarity as that of the toner is applied. The toner remaining on the peripheral surface is cleaned. A fixing device 4 includes a heating roller 40 including a halogen heater and a pressure roller 40b.

  Reference numeral 7 denotes a paper feed conveyance path which is a first paper conveyance path for forming a single (front) surface image, 70 is a paper feed roller, and 71 is a pair of conveyance rollers provided with pressure adjusting means 9A (see FIG. 3). The timing roller is configured such that one is a paper feed roller 710 and the other is a driven roller 711. Reference numeral 72 denotes a paper feed cassette, and 73 denotes a conveyance roller.

  81 is a paper discharge roller, and 82 is a paper discharge tray. Reference numeral 85 denotes an operation panel.

Reference numeral 9 denotes an ADU mechanism that includes a conveyance path that is a second sheet conveyance path for a transfer material when double-sided image formation is performed.
B1 is a control unit as a control unit for each drive unit, image forming process, fixing temperature, and paper feed guide member adjustment described later.

  Hereinafter, the image forming process (image forming process) will be described with reference to FIG.

  At the start of image recording, the photosensitive drum 10 of the yellow (Y) image forming means 1 is rotated in the direction indicated by the arrow by starting the driving motor of the photosensitive drum (not shown), and at the same time, the photosensitive member is charged by the scorotron charger 11. Application of a potential starts at 10.

  After the photoconductor 10 is applied with a potential, image writing by an electric signal corresponding to the first color signal, that is, Y image data is started by the writing device 12, and a Y image of the original image is formed on the surface of the photoconductor 10. An electrostatic latent image corresponding to is formed.

  The latent image is reversed and developed in a non-contact state by the developing device 13, and a yellow (Y) toner image is formed according to the rotation of the photoreceptor 10.

  The Y toner image formed on the photoreceptor 10 as an image forming body by the image forming process is transferred onto the intermediate transfer belt 20 by the transfer unit 25.

  Next, the intermediate transfer belt 20 is synchronized with the Y toner image, and a potential is applied by the charging action of the scorotron charger 11 by the magenta (M) image forming means 1, and the M color signal, Image writing is performed by an electrical signal corresponding to the M image data, and the M toner image formed on the photoreceptor 10 by non-contact reversal development by the developing device 13 is transferred by the M transfer unit 25 to Overlaid from above the Y toner image.

  A similar process is used to synchronize with the superimposed toner images of Y and M, and corresponding to the C image data based on the C color signal formed on the photoreceptor 10 by the cyan (C) image forming means 1. A C toner image is formed by being superimposed on the Y, M, and Y toner images by the C transfer unit 25, and is further synchronized with the Y, M, and C superimposed toner images. K) The toner image corresponding to the K image data based on the K color signal formed on the photoconductor 10 by the image forming means 1 is transferred onto the Y, M, C, A toner image of K is superimposed and formed on the toner image, and a superimposed color toner image of Y, M, C, and K is formed on the intermediate transfer belt 20, respectively.

  Further, the toner remaining on the surface of the photoreceptor 10 of each color after the primary transfer is removed by the cleaning unit 14, and the photoreceptor 10 in the previous image formation is performed by a uniform exposure device (not shown) before charging. The history is canceled and the next image forming cycle is started.

  The intermediate transfer belt 20 carrying the superimposed toner image is sent in the direction of arrow F, and the transfer material P is sent out by a feed roller 70 from a paper feed cassette 72 which is a transfer material storage means, and a transport roller 73. Then, it is conveyed to the timing roller 71 provided in the first sheet conveyance path, synchronized with the toner image on the intermediate transfer belt 20, and fed to the transfer area S of the transfer roller 26 by driving the timing roller 71. The

  The transfer material P superimposed on the intermediate transfer belt 20 is nipped and transferred between the earth roller 22 and the transfer roller 26 in the transfer region S. In the fixing device 4, the transfer material P carrying the toner image is sandwiched and pressed between the heating roller 40 and the pressure roller 40 b to be fixed.

  In the case of single-sided image formation, the transfer material P is sent to the paper discharge guide 83 by the conveyance switching valve 92 that is in a one-dot chain line state in FIG. 1 and is discharged from the paper discharge roller 81 to the paper discharge tray 82. In the case of double-sided printing, after the fixing, the transfer material P is lowered by the conveyance switching valve 92 in a state indicated by a solid line, conveyed to the curved conveyance path 90 by the conveyance roller 92a, and enters the ADU mechanism unit 9. Then, the paper is sent to the paper reversing path 90a by the transport rollers 92b and 92c. In the paper reversing path 90a, after the transfer material trailing edge is temporarily held and the conveyance roller 92c is reversed, the transfer material trailing edge becomes the leading edge and is reversed by a conveyance switching valve (not shown). Proceed to roller 92d and transport path 90b. Further, the conveying rollers 90e and 90f are sent to the timing roller 71, which is a conveying roller pair having the pressure adjusting means 9A, to temporarily stop, and are transferred to the toner image on the intermediate transfer belt 20 in synchronization. Thereafter, the paper skew is corrected by the driving of the timing roller 71 and fed to the transfer area S of the transfer roller 26, and then discharged in the same process as in the case of single-sided printing.

  Here, the pressure adjusting means 9A of the timing roller 71 which is a pair of conveying rollers according to the present invention will be described.

  Paper curving tends to occur especially on curved conveyance paths. In this embodiment, the pressure adjusting means for the conveying roller pair is applied to the timing roller 71. Further, the position detection sensors S1 and S2 for detecting the bending of the paper are provided in the straight conveyance unit of the conveyance path. The position detection sensors S1 and S2 are area sensor elements composed of CCDs and are arranged on the conveyance path. The detection value detected by the position detection sensor S1 and the detection value detected by the position detection sensor S2 are used to detect paper bending in the conveyance direction of the transfer material, and the detected position signal is sent to the control unit B1 and The amount of paper bending is calculated based on the difference between the detection values. The amount of paper bending is corrected by a timing roller having a pressure adjusting unit as shown in FIG.

  FIG. 2 is a diagram illustrating the transfer material P and a position detection sensor that detects a position in the straight-ahead conveyance unit.

  In FIG. 2, the position detection sensor S1 (see FIG. 1) detects that the transfer material P indicated by the alternate long and short dash line is bent as indicated by the dotted line when passing through the position detection sensor S2. θ can be calculated. That is, the amount of bending θ is the amount of bending that occurs when the transfer material P passes through the position detection sensor S1 and then passes through the curved portion of the ADU mechanism unit 9 and reaches the position detection sensor S2 during double-sided image formation. Indicates.

  FIG. 3 shows an enlarged view of the pressure adjusting means applied to the timing roller in FIG.

  3A is a view as seen from the transfer material conveyance direction, and FIG. 3B is a cross-section as seen from the X direction of FIG.

  In FIG. 3, reference numerals 7A and 7B denote frames of the paper feed main unit. The timing roller 71 slides in the direction of the arrow Y engaged with the rubber paper feed roller 710 supported via bearings fixed to the frames 7A and 7B and the elongated holes V of the frames 7A and 7B. The roller driven roller 711 is supported via a bearing, and is in a state in which the roller shaft end portion on the frame body 7A side is pressed against each other by a pressure spring 718. The paper feeding roller 710 is supplied from a driving unit (not shown). Rotate with the power of. A bearing 713 is pivotally attached to the frame 7B side of the rotation shaft 712 of the driven roller 711, and the bearing 713 is in contact with an eccentric cam 714 integrated with the cam rotation shaft 715. Further, an operating gear 716 is attached to the cam rotation shaft 715, and is rotated by obtaining a rotating force from the stepping motor M through a series of gear groups, and the eccentric cam 714 is rotated by a predetermined angle. In other words, the axial pressing force balance of the other driven roller 711 with respect to the one paper feeding roller 710 can be adjusted by the rotation angle of the eccentric cam 714, and the paper bending of the transfer material sandwiched between the rollers is corrected. be able to.

  Although the deviation of the transfer material remains even if the paper bending is corrected, the reference position is changed by displacing the writing position (writing timing in the main scanning direction) of the writing device 12 in accordance with an instruction from the control unit B1. The image position can be secured.

  That is, the position information detected by the position detection sensors S1 and S2 is transmitted to the control unit B1. The control unit B1 calculates a difference between detection values (paper bending amount) based on position information obtained from both sensors S1 and S2. Then, the control unit B1 drives the stepping motor M to change the pressing force between the paper feed roller 710 and the driven roller 711 according to the calculated value so that the subsequent transfer material does not bend the same paper. Control. By driving the stepping motor M, the eccentric cam 714 rotates by a predetermined angle, and changes the pressing force of the driven roller 711 against the paper feed roller 710. As a result, the balance of the axial pressing force of the driven roller 711 with respect to the paper feed roller 710 is changed, and paper bending is suppressed when the subsequent transfer material is conveyed. Thereby, at the time of double-sided image formation, the posture of the transfer material when the image is formed on the first surface of the transfer material and the posture of the transfer material when the image is formed on the second surface can be made the same. Can be prevented from occurring between the first image and the second image. In the light printing area, an image output with a very high quality at the offset printing level is required, and the required accuracy for the inclination of the image on the second surface with respect to the image on the first surface when forming a double-sided image is very high. According to the image forming apparatus of the present invention, the inclination of the image on the second surface with respect to the first image can be suppressed with high accuracy.

  Further, after the transfer material is detected by the position sensor S2, when the transfer material reaches the position detection sensor S1 again, the transfer material is detected by the position detection sensor S1, and the detected value in the position detection sensor S2 and the position detection sensor S1. The difference between the detected value and the detected value is calculated by the control unit B 1, and the eccentric cam 714 is rotated in accordance with the calculated value to further change the pressing force of the driven roller 711 against the paper feed roller 710. Accordingly, the transfer material can be prevented from being bent due to the curvature of the paper feed guide member 93 after passing through the position detection sensor S2, so that the inclination of the image on the second surface with respect to the image on the first surface can be suppressed with higher accuracy. it can.

  The control unit B1 stores a program relating to the amount of displacement of the pressing force of the roller according to the value of the amount of paper bending. Based on this program, the control unit B1 drives and controls the rotation of the stepping motor M to change the pressing force of the rollers. Further, the writing start timing corresponding to the shift amount of the transfer material in the main scanning direction is also stored as a program in the control unit B1.

  In the embodiment, the pressure adjusting unit is applied to the timing roller 71 during double-sided image formation. However, for example, the conveyance rollers 92e and 92f are located upstream of the position detection sensor S1 and downstream of the position detection sensor S2. You may apply to.

  Further, in an image forming apparatus only for single-sided image formation, the press adjusting means of the present invention is applied before image transfer onto a transfer material to correct paper bending and to match the timing of writing on the image carrier. You can also.

  Further, the present invention can be applied not only to an electrophotographic image forming apparatus but also to an image forming apparatus such as an ink jet printer.

1 is a schematic diagram illustrating an example of an overall configuration of an image forming apparatus. It is a figure which shows the transfer material P in a rectilinear conveyance part, and the position detection sensor which detects a position. The figure which expanded the press adjustment means applied to the timing roller in FIG. 1 is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 7 Paper feed conveyance path 7A, 7B Frame 71 Timing roller 710 Paper feed roller 711 Drive roller 713 Bearing 714 Eccentric cam 715 Cam rotation shaft 9 ADU mechanism part 90, 90b Carriage path 90a Paper reversing path 92 Transport switching valve 92a, 92b, 92c, 92d, 92e, 92f Conveying roller B1 Control unit M Stepping motor S1, S2 Position detection sensor

Claims (5)

An image forming apparatus comprising a pair of conveyance rollers for conveying a recording material to a conveyance path for conveying a recording material, wherein the conveyance roller pair is capable of displacing an inclination with respect to an axial conveyance surface. The conveyance path includes a first sheet conveyance path for single-sided image formation and a second sheet conveyance path for double-sided image formation connected to the first sheet conveyance path, and the first sheet conveyance path and the The image forming apparatus according to claim 1, further comprising: a position detection sensor that detects a recording material in the second paper conveyance path, and the position detection sensor detects a skew amount with respect to a conveyance direction of the recording material. apparatus. A pressure adjusting unit that adjusts the pressure on the pair of conveying rollers, and a control unit that compares detection values detected by the position detection sensors of the respective sheet conveying paths, and based on a signal from the control unit, The image forming apparatus according to claim 2, wherein the pressure adjusting unit is controlled. One of the pair of transport rollers is slidably supported toward the other transport roller, and one end side in the axial direction of the one transport roller is urged by an elastic means in the direction of the other transport roller, 4. The image forming apparatus according to claim 1, wherein the other axial end is configured to be displaceable by a pressing adjustment unit. An image forming apparatus including a pair of conveyance rollers for conveying a recording material to a conveyance path for conveying a recording material, wherein one of the conveyance roller pairs is configured to be capable of adjusting a pressing force balance with respect to the other in an axial direction. Image forming apparatus.

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